Electromechanical clock



O. H. DZCKE.

ELECTROMECHANICAL CLOCK 2 Sheis-Sheet 1 Filed June 29. 1949 [nimuuuumHfa INVENTOR Oscar H. Dl'cke W if? iane 12, 1954 G. H. mc

ELECTROMECHANICAL CLOCK 2 Sheets-Sheet 2 F'kecl June '29. 1949 Rm r m Nm &

"WU G i Patented Jan. 12, 1954 UNITED STATES PATENT OFFICE Claims.

This invention relates to clock mechanism for very accuratelymanifesting the passing of time including time-keeping mechanism whichmeasures the passing of time irrespective of an alternating currentcessation which is both automatically set and automatically regulated byalternating current of regulated frequency.

At present substantially all alternating current commercially generatedhas its frequency regulated so that its average frequency correctlymanifests the passing of time. There are two shortcomings to suchalternating current as a time keeping source. 1) This source of currentat times fails; and (2) the frequency is not suificiently constant tomeasure extremely short intervals of time since it is the averagefrequency and not the instantaneous frequency that correctly manifeststhe passing of time.

In accordance with the present invention it is proposed to employ clockmechanism which may be fairly well relied upon to keep accurate timewhen properly adjusted which is provided with regulating means by themanipulation of which the time keeping speed of the clock may beadjusted, to provide means automatically operated in accordance with theaverage frequency of an alternating current of regulated frequency tooperate this regulating means to a position to cause said clockmechanism to correctly manifest the passing of time and to additionallyprovide means for at spaced time intervals setting the clock hands ofsuch clock mechanism in accordance with the number of cycles ofalternating current that have been supplied since the last settingoperation.

Another object of the present invention resides in performing both ofthese functions with the same synchronous motor.

Another object of the present invention resides in performing theregulating function in a manner so that a regulating function that hasonce been performed is not interfered with as a result of an alternatingcurrent cessation.

Another object of the present invention resides in providing means tobring the synchro nous motor operated mechanism back into chronologicalsynchronism with the clock mechanism after each current cessation.

Another object of the present invention resides in providing settingmeans which does not interfere with the free and proper operation ofboth the clock mechanism and the synchronous motor operated mechanism.

Other objects, purposes and characteristics of the present inventionwill become apparent from 2 the following specification when consideredin the light of the drawings in which:

Figs. 1 and 1a show one conventional embodiment of the present inventionin a manner to facilitate description of the various mechanisms andtheir functions rather than the exact construction preferably used inpracticing the invention.

Structure.-Referring to the drawings the main spring [0, which may bewound in any suitable way, drives the gear i! which through its shaft109 drives the pinion Hi2, which is in mesh with gear Hll. Gear it!through the medium of slip clutch I04 drives shaft 193 having securedthereto a gear I05 and a setting arm I35. A minute hand I36 is showndriven by a gear 99 driven by gear 105 at a one-to-one gear ratio. Anhour hand I3Ga R. P. H.) is driven by the gear 99 through the medium ofthe usual hour-hand reduction gearing shown. The gear I05 is also inmesh with gear [06 having the same number of teeth as gear I95. Thisgear I06 has secured thereto a cam H2 preferably of insulating material.This main spring gear II also drives the pinion I2 which is connected byshaft 9 to gear I3 in mesh with pinion l4. Pinion [4 through shaft [5drives gear 16 in mesh with pinion I! which through shaft !8 drivesescape wheel IS.

The escape wheel 19, tends to oscillate the pallet 29. This pallet ispivoted at 2i and supports two laterally projecting pins 22 located onopposite sides of a flat leaf spring 23. This leaf spring 23 supportspendulum 2d and has its upper end secured to a preferably squarethreaded shank 25 which has its threads supported by the threadscontained in the axial opening of a worm wheel 26. This worm wheel 26 issupported by and the shank 25 is guided in a fixed support 28. It isthus seen that the effective length of the pendulum 23-4 is changed asthe worm wheel 26 is rotated. The worm wheel 26 is driven in onedirection or the other (and at times remains stationary) by the worm 21secured to gear 30. Gear 30 is at times driven by pinion 3! driven byfriction wheel 33 through the medium of shaft 32. Another friction wheel34 is pivotally supported in a spider 35 pivoted on a fixed pin 36 onwhich there is also pivoted a pinion 37 in meshed relation with a gearMa secured to friction wheel 34. When electromagnet 40 is energized byalternating current (or direct current derived from such alternatingcurrent) the spider 35 assumes the position shown and holds the frictionwheel 34 in driving The pinion 32' is at times driven by the pinion 2meshed relation therewith, which pinion 2 is connected to worm wheel itthrough the nediurn of shaft Q3. Worm wheel-cf; isdr-iven by worm G onshaft whichiaas-bya pin connected to the ring wheel or planet supportingwheel This ring wheel 'll le -provided with stub shafts, which havetheir axis arranged radially and on which are pivoted planet pinions to.Two bevel gears 5i and-52 .arepivotally supported on sha'ft lt. A wormwheel 53 is secured, to bevel gear '5! and a worm wheelfi i is securedto or integral-with bevelgear 52. Both of these bevel gears-Ell and 52are in meshed relation with planet pinions til. From this cons ructionit is readily seen that if wormwheels es and Eli are rotatedatclifierent speeds and in opposite directions the ring wheel Al isrotated at a sp-eed'equal to the diirerence of the speed of rotation ofworm wheels 53 and 5s, and if rotated at the same speed the ringwheel lland shaft to remainstaticnary. As shown by the arrowsgthe'worinwheels'53 and are rotated in opposite directions, :the'worrn wheel 53 beingdriven by theworrn 6!) cut into shaft iii to which worm wheel EZis.connected and the worm wheel 54 by worm "ill on shaft "H. The

worm wheel is driven by worm-63 cut on shaft I t5 having a worm wheel 65securedzthereto and driven by a worm is cut into shaft .15 or" theescapement clock. Similarly the wormwheel its is driven in the oppositedirection by worm 778 out into shaft ll, driven by worm wheel '52,driven by worm is cut into sha'ft'l-l tor synchronous motor SM. Thespeeds oi'the shafts i l and Hill and the gear ratios from 'these'shaitsto the worm wheels Eli and 53 respectively are such that the worm wheels53 and 513 rotate at the same speed, and in opposite directions whentheclock. mechanism keeps perfect time and when exactly sixty cyclealternating current is .applied to synchronous motor SM. When these wormwheels 53 and 5t and their'associated bevel gears ill and 5:2 rotate atdifferent speeds the ring wheel ll'will rotate-at'the difierenc'e 'ofthetwo speeds to thereby cause operation or the gear train between shaftand pendulum ad.- justing worm wheel 26. These various gear ratios aresuch that if the'clock mechanism gains one minute in 48 hours /2minute'per day) the pendulum will be lengthened, 'soas to gain onlyone-half minute in 48'hours after '8 hours of operation. In other wordsthe gear ratio is such as to make a half correction in 43 hours;

The synchronous niotor SM also sets the clock hands to and 38aassociated'with the escapeznent clock mechanism. To perform this settingfunction the shait'l l of the synchronous motor SM.

is provided with 'a pinion l2! which drives the gear 222 secured toshaft lllssupported'in'fixed bearings 88, 89 and 538. On this shaft ispivotally supported a sleeve I0! which supports gear its and slip ringHi The shalt 108. supports a preferably square block 926 to which a leafspring l2? is secured. The other or free end of this leaf springsupports a setting arm E so that the leaf spring liil constitutes aspring bearing fulcrum. During operation of shaft Hit the setting armE25 is urged against and rides against the fixed spiral cam ltd, itbeing urged thereagainst by the spring are. At the end of each hour, orother suitable time period as determined by the synchronous .motoroperated portion of the clock mechanism, the setting arm 525 snaps offor the leaving end or cam and onto the starting end of this cam and inso doing causes the open v-shaped hammer, constituting two obliquelyarranged arms 225d, to set the setting arm I to the proper chronologicalpositionif it doesnot already assume such position.

Each time that an alternating current cessation occurs the setting armits will discontinue rotating at least so long as the currentcessationoontinues. If-itwere to start rotating'when alternatingcurrentflow is resumed itwould not indicate the proper time insofar asthe minutes within an hour is concerned. For reason thesynchronous'inotor SM and in turn the arm E25 is prevented from rotatinguntil the shaft lee rnanifests'the same chronologicalcondition as doesshaft H33. This critical starting of the synchronous motor Sh iaccomplished by the snap action contact lit-M 1. The gear which isinmeshed relation with gear Bills-supports'a cam H2 having abeal-zed endii a, both preferably of insulating material, at the'end of which thereis a flexible contact M3. To the shaft N38 is secured an arm lit,preferably of insulating material, having a projecting crank membersupportin a spring contact ll l which is locatezl'to ride on theinsulated cam ii? and beak HM and which will when it reaches'the end ofthe beak H211 snap by the end and-momentarily engage the contact H3.This momentary engagement of contacts 2 it and'l i l-oc- 'lClllSwhen'the shaft its and the sleeve it? as- .sume the same chronologicalposition about the axis of these'eleinents.

On the sleeve iil'l is secured a slip ring Hi3 which is connected bywire M3 to contact H3. Similarly the shaft 595 is provided with a slipring 109 connected by wire 12% to contact HQ. The contacts H3-l i lconstitute a picl in circuit closer for synchronous motor SM, whereasthe contact I29 associated with the magnetic circuit of thismotor SM isclosed only when the synchronous motor SM is energized and thereforethis motor will continue to have its energizing-circuit closed. until analternating current cessation occurs. The reference character A. C.signifies a source of alternating current having its frequencyregulated'so that its average frequency correctly manifests the passingof time. Attention is directed to the fact that the winding of motor SMis connected in multiple with the coil of electro-rnagnet all. Ifdesired this winding and coil may be connected in series. vAlso thecontact 129 is a holding contact which is, as shown, closed in responseto activation of the magnetic field of'rnotor SM. If desired thiscontact I26 may be associated with the electromagnet w and closed whenthe coil of this electro-magnet to is energized, When contact lill isclosed both the electro-magnet' lii and the synchronous motor SM areenergized directly from the alternating current source, there being noothercontacts in the energizing circuits, and they will both remainenergize-:1 until a cessation in the supply of alternating currentoccurs. When an alternating current cessation occurs both of theseenergizing circuits are broken by the opening of contact I20 and willremain broken even though the supply of alternating current is restored.It is only in response to the momentary closure of contacts I I3I I4that the motor SM and/or the electromagnet 40 can be re-energized.

Operation-Let us assume, for the purpose of discussion, that theescapement portion of the clock mechanism has the length of its pendulumso adjusted, presumably in the course of manufacture, so that it runsfast'to an extent of onehalf minute per hour (gains twelve minutes perday). Also, that the synchronous motor SM and electro-magnet 40 are bothdeenergized because the contacts I I3I I4 have not yet been momentarilyclosed since the alternating current source was wired to the clockmechanism. Let us also assume that the clock hands I36 and I 360;indicate 11:58 p. m. the correct time and that the synchronous motormechanism by its clock hand I31 indicates 11:50 p. m. One minute later,namely, when both the escapement portion and the synchronous motorportion of the clock mechanism indicate 11:59 p. m. the contact H4 dropsoff of the beak II2a down to the low portion of the cam I I2 and in sodoin this contact H4 momentarily engages the contact II3. momentaryengagement of these contacts H3 and H4 causes energization of motor SMand electro-magnet 40 and causes closure of contact I irrespective ofwhether this contact I20 is associated with the synchronous motor SM orthe electromagnet 40. A pick-circuit is then closed from the source A.C. wires I52 and I52, slip-ring I09, wire I24, contacts H4 and IE3, wireI23, slip-ring IIO, wires I53, I54 and I55 winding of synchronous motorSM wire I56 back to the source A.. C. Also, in multiple with Wires I55and I56 going to the synchronous motor SM are wires I55a and I56aextending to electromagnet 40. As soon as contact I20 closes the pick-upportion of the circuit just traced and including contacts II3-I I4 isshunted out by a stick circuit branch including wires I5! and I58 andholding contact I20. The synchronous motor portion of the mechanism andincluding shafts "I4 and I08 and gears I2I and I22 are now operating aswell as gear I05 which was always operating. One minute later, namely at12:00 midnight, the setting arm I25 snaps on" of the leaving end of camI and in so doing sets the escapement clock portion of the clockmechanism and including shaft I03, gears 09, I05 and I00 and clock handsI36 and I30d.

it should be observed that the gears I0! and 122 as well as the arms IISand I25 on shaft I08 are not afiected in any way by this settingoperation by reason of slip clutch I04 and the idling of gear I00 onshaft I08. In this particular instant the setting arm I already assumedsubstantially the position mid-way between the two V-portions I25a ofthe setting arm I25 in that the accumulative error during one minute ofoperation is very small and little change in the positions of clockhands I36 and I 26a took place. When the setting arm I35 is slightlytoward one side or the other an effective setting operation will takeplace.

One hour later, namely at 1:00 a. m., as indicated by the synchronousmotor clock-hand I37 the clock hands I 35 and I 36a indicate about 29seconds past one oclock in the morning. They This U would have indicatedabout 30 seconds past one oclock were it not for the fact that theescape ment portion of the clock mechanism keeps slightly better timethan it did formerly in that the pendulum 24 has been lengthened alittle during the past hour. This was accomplished because worm wheel 53rotated a little faster than worm wheel 54 and in so doing rotated thering wheel 4'! in a direction to lengthen the effective length of theleaf-spring constituting part of the pendulum 2324. In this connectionit should be remembered that the electromagnet 40 was energized for thepast hour and therefore held the friction wheels 33 and 34 in drivingengagement so that the rotation of rin wheel 4'! was eiiectivelytransmitted, at a greatly reduced speed, to the worm wheel 25 directlyabove the pendulum. At this instant (1:00 a. in. alternating currenttime) the setting arm 25 snaps off of the leaving end of cam E30 andonto the starting end of this cam and in so doing sets the clock handsI35 and 1300; backward to an extent of about 29 seconds, and both setsof clock hands now indicate 1:00 a. m. and correct time. Hour afterhour, or any other suitable time period, this setting operation isrepeated but in each case the escapement mechanism gains less than itdid during the preceding hour. At midnight of the second day, namelyforty-eight hours after the clock was set manually and wired to thecommercial alternating current source of regulated frequency, thependulum 24 has been lengthened to an extent where the escapementportion of the clock mechanism gains only fifteen seconds per hourinstead of thirty, If we assume that no power failure occurs for anothersix-day period (eight days altogether and a fair assumption) theescapement clock will have been regulated toward correct time keeping toan extent where it only gains one and seven-eighths seconds per hour,but it still indicates correct time at the end of each hour by reason ofbeing set periodically by the synchronous motor mechanism.

Let us now assume that at 12:01 a. at the beginning of the ninth day, analternating current cessation occurs and that the cessation continuesfor 29 minutes. When at 12:30 a. in. power comes back on and alternatingcurrent is again available nothing in particular happens and so it couldjust as well have remained off a much longer time. Nothing happensbecause the alterhating current that is available cannot reach eitherthe synchronous motor SM nor the electromagnet 40. However, at 1:01 asmanifested by the escapement clock the spring contact 5 M snaps off ofthe end of the beak Him and in so doing momentarily engages the contactH3 to thereby energize both the synchronous motor SM and theelectro-magnet 40 after which both of these electro-responsive deviceswill remain energized through the medium of closed holding contact I20.Both the escapement portion and the synchronous motor portion of theclock mechanism now manifest the same time, both are however one andseven-eighths seconds fast because the escapement clock was gaining atthe rate of one and seven-eighths seconds per hour during the hour whenthe synchronous motor SM was deenergized and at rest. That is, the timekeeping quality of the clock was improved in four two-day periods togains of 15 seconds, 7% seconds, 3% seconds and 1% seconds per hour. At2:00 a. as manifested by the synchronous motor portion of the clockmechanism the clock installation.

tafeesgaas J hands i315 tand [35a were again set by the :settingrnechanism i rib-E35 but after such setting fun'ctionthe 'clocl; handsfist-i360, are stillone anld seven-eighths seconds fast becausethe'synchronous motor SM was started one andseveneighth's seconds beforeone hour had elapsed after the current cessation started. In otherwords, if a clock automatically regulated and periodically set inaccordance with this invention is installed on a customers premises ex-'less than one second during'each hour after the tenthday. If, however,a current cessation occurs at the end of the eighth day, as aboveassumed, the clock mechanism will have the same time keepingcuality butthe clock 'mechanism will be one and seven-'eighths seconds fast forreasons above given.

The main spring it may be wound manually by the usual winding key andratchet holding mechanism or may be wound automatically by any one ofthe various electric winding mecha nisms well known in the art, or ifdesired may be wound by the synchronous motor SM through the medium ofreduction gearing including a slip clutch. V i

It should be understood that the synchronous motor starting and theclock setting function is not necessarily performed on an hourly basisas specifically disclosed but may be performed on any desired timeperiod basis. Also, other forms of mechanism than that shown may beused.

The exact gear reduction from the differential DF to the worm wheel 26associated with the pendulum support 23 cannot'be given because thescrew pitch in the hole of the worm wheel 26 is a factor, as is also thenormal speed of rotation of worm wheels iSand d of the'differential DF.Themost accurate way of stating this gear ratio 'istosay' that it issuch as to cause the pendulum to change .in length to an extent that itstime keeping error will be corrected, that is, reduced fifty percent foreach, say, forty-eight hours of regulation. This correction is purposelymade extremely slow so that proper averaging of the alternating currentfrequency will result and also so that small variations in frequencywill produce substanti no effect insofar as adjustment of the'pendulumlength is concerned. This phase of the automatic regulating feature ofthe present clock mechanism is more fully'described in my priorapplication Serial No. 101334 filed June 29, 1949, to which attention isdirected. Stating it briefly the regulating function is carried out sogradually that the escapement mechanism will be adjusted to the averagefrequency andnot so fast? as to follow variations in frequency.

It should be understood that the timekeeping portion of the presentinvention is not necessarily an escapement pendulum clock but may be anescapement clock of the hair-spring balancewheel type or may, in fact,be of any suitable construction so long as it has good time keepingualities and provided that it may beregulated while'in operation.

It should be understood that the setting feature of the presentinvention may be used'separately'from the regulating feature and viceversa.

Having thus shown and described only one -specific embodiment of thepresent invention it should 'be understood that the particularembodiment shown has been selected to facilitate a description of theunderlying principles of the invention and how'these principles may becarried out inpracticing the invention; and that various changes,modifications and additions may be made in practicing the invention solong as these changes do not depart from the spirit or scope of theinvention as defined by the scope of the following claims.

'What'I claim as new is:

1. Time manifesting apparatus comprising;

"clock mechanism including a gear train, a slip clutch, clock handsrotated by said gear train through the medium of said slip clutch, meansfor driving said gear train tending to drive it at excess speed,governing means for retarding the speed of operationof said gear train,regulating means for controlling the speed limit imposed by saidgoverning means; a source of alternating current of regulated frequencyso regulated that its average frequency correctly manifests the passingof time; a second gear train; a synchronous motor for operating saidsecond gear train; means including one contact operated by said clockmechanism and a second contact assuming a position dependent on theposition then assumed by said second gear train for at least momentarilyconnecting said synchronous motor'to said source of alternating currentwhen said second gear train and said clock hands manifest the same time;means including a holding contact for maintaining said synchronous motorconnected to said source of alternating current when said synchronousmotor has been once energized until a cessation of alternating currentoccurs; means controlled by said second gear train for periodicallysetting said clock hands to the same chronological condition as thatmanifested by the second-gear train as permitted by said slip clutch,and means controlled jointly by said two gear trains for operating saidregulating means to an adjusted position relatively slowly to cause saidclock mechanism after a relatively long'period to be adjusted to operaleat a speed to cause said clock hands to correctly manifest the passingof time as manifested by the average frequency of said alternatingcurrent source.

2. Time manifesting apparatus comprising; clock mechanism including agear train, a slip clutch, clock hands rotated by said gear trainthrough the medium of said slip clutch, means tending to drive said geartrain at an excessive speed, governing means for retarding the speed ofoperation of said gear train, regulating means to control said governingmeans; a source of alternating current having its frequency so regulatedthat its average frequency correctly manifests the passing of time;a-second gear'train; a synchronous motor for operating said second geartrain; contacts assuming relative positions dependent on the relativepositions assumed by said second gear train and said clock hands andclosed momentarilywhen said second gear train and said clock handsassume the same chronological condition included in an energizingcircuit for said synchronous motor; a holding concal position as thatmanifested by said second gear train as permitted by said slip clutch;and means controlled jointly by said two gear trains and in accordancewith the difference of their speeds of rotation for operating saidregulating means to an adjusted position relatively slowly to cause saidclock mechanism after a relatively long period to operate at a speed tocause said clock hands to correctly manifest the passing of time asdetermined by the average frequency of said alternating current source.

3. Time manifesting apparatus comprising, clock mechanism provided withclock hands frictionally connected by a friction slip clutch to saidclock mechanism, a source of commercial alternating current having itsfrequency reguiated so that its average frequency correctly manifeststhe passing of time, synchronous motor mechanism including a synchronousmotor energized from said source of alternating current for periodicallysetting said clock hands as permitted by said friction slip clutch solong as no current cessation occurs, means for preventing the restartingof said synchronous motor upon the restoration of the alternatingcurrent until at an instant one setting period after such currentcessation started, and means for maintaining said synchronous motorenergized until a cessation of such alternating current occurs.

4. Time manifesting apparatus comprising, clock mechanism including atime shaft, clock hands, a friction slip clutch for driving said clockhands by said time shaft, a source of alternating current having itsfrequency regulated so that its average frequency correctly manifeststhe passing of time, a synchronous motor at times connected to saidsource of alternating current, setting means controlled by saidsynchronous motor for periodically setting said clock hands as permittedby said slip clutch and only so long as no current cessation occurs,means for temporarily preventing the energization of said synchronousmotor after a current cessation and reenergizing said synchronous motorafter the termination of such cessation only at an instant when saidclock mechanism manifests the same chronological condition as ismanifested by said setting means, and means for maintaining saidsynchronous motor energized until a cessation of such alternatingcurrent occurs.

5. Time controlled mechanism comprising, a clock mechanism having afriction clutch and clock-hands frictionally connected to said clockmechanism by said friction clutch and provided with regulating means forregulating its speed of operation, a source of alternating currenthaving its variable frequency regulated so that its average frequencycorrectly manifests the passing of time, a synchronous motor, a shaftdriven by said synchronous motor and rotated at a speed of onerevolution in a particular period of time as manifested by the averagefrequency of said alternating current source during such period of time,a shaft driven by said clock mechanism at a speed of one revolution inthe same period of time but as manifested by said clock mechanism,contacts including contacts operated by said shafts and a holdingcontact for connecting said synchronous motor to said source ofalternating current only when said shafts assume the same chronologicalposition and maintaining it connected until and only until analternating current cessation occurs, setting means controlled by theshaft driven by said synchronous motor for setting said clock-hands aspermitted by said friction clutch periodically to the same chronologicalcondition as manifested by the shaft driven by said synchronous motor,and means controlled jointly by said clock mechanism and saidsynchronous motor for operating said regulating means relatively slowlyin accordance with the difference of the times manifested by said clockmechanism and said synchronous motor and after a relatively long periodof time cause said regulating means to be adjusted to a condition tocause said clock mechanism to correctly manifest the passing of time asdetermined by the average frequency of said alternating current sourceover such relatively long period of time.

6. Time controlled mechanism comprising, clock mechanism including afriction clutch and clock-hands frictionally connected thereto by saidclutch and provided with regulating means for regulating its speed ofoperation, a source of alternating current having its frequencyregulated so that its average frequency correctly manifests the passingof time, a synchronous motor, a shaft driven by said synchronous motorand rotated at a speed of one revolution in a particular period of timeas manifested by the average frequency of said alternating currentsource, a shaft driven by said clock mechanism at a speed of onerevolution in the same period of time but as manifested by said clockmechanism when its regulating means is correctly adjusted, contactsoperated respectively by the two shafts and connecting said synchronousmotor to said alternating current source by being closed momentarilywhen said shafts assume the same chronological rotated 13051131011,holding contacts for maintaining said synchronous motor so connecteduntil and only until an alternating current cessation occurs, settingmeans driven by the shaft driven by said synchronous motor forperiodically setting said clock hands as permitted by said frictionclutch, and adjusting means controlled jointly by said clock mechanismand said synchronous motor for adjusting said adjusting means relativelyslowly in accordance with the difference of the times manifested by saidclock mechanism and said synchronous motor and for operating saidregulating means to cause said clock mechanism after a relatively longperiod of correction to correctly manifest the passing of time asdetermined by the average frequency of said alternating current sourceover said relatively long period, and means for rendering said lastmentioned means Wholly ineffective to adjust said adjusting means solong as said synchronous motor is deenergized.

7. Time controlled mechanism comprising, time lapse manifesting meansdriven from a local source of energy including a shaft rotated at aspeed of one revolution in a predetermined pe 10d of time as measured bysaid means and including a friction clutch and clock-hands frictionallydriven thereby, a source of alternating current of regulated frequencyhaving its varying frequency so regulated that its average frequencyover relatively long periods of time correctly manifests the passing oftime, a synchronous motor, a shaft driven by said synchronous motor at aspeed of one revolution in said predetermined period of time asmanifested by the cycle passage of said alternating current, twocontacts supported respectively by the two shafts for connecting saidsynchronous motor to said source of alternating current closedmomentarily when said shafts assumo the same chronological position ofrotation, holding contacts for maintaining said motor so 11" connectedso long and only so long; as no alter nating current cessation occurs,and setting means controlled by the shaft driven by said synchronousmotor for periodically setting said clock-hands to the samechronological position as manifested by the shaft driven by saidsynchronous motor as permitted by said friction clutch.

8. Time manifesting apparatusv comprising, mechanical time measuringapparatus, electrical time measuring apparatus including aself startingsynchronousmotor, and contact mechanisms for allowing the restarting ofsaid synchronous motor after a current cessation only when saidmechanical and said electrical time measuring apparatuses assume thesame chronological condition, means for maintaining said synchroe nousmotor energized until. and only until a cessation of alternating currentsuppliedto said synchronous motor occurs, and means governed by saidelectrical time measuring apparatus for setting said mechanical timemeasuring apparatus periodically.

9. Time manifesting apparatus comprising, mechanical time measuringapparatus, a source of alternating current having its frequencyregulated so that its average frequency correctly manifests the passingof time, electrical time measuring apparatus including a self startingsynchronous motor at times connected to said source, contact mechanismsfor starting said syn.- chronous motor only when said mechanical andsaid electrical time measuring apparatuses assume the same chronologicalcondition, means for maintaining said synchronous motor energized untila cessation of alternating current supplied to said synchronous motoroccurs, and means controlled by said. electrical time measur- 32 mg,apparatusfor periodically setting saidmechanical time measuringapparatus.

10. Time manifesting apparatus comprising,

mechanical time measuring, apparatus, a fric tion slip clutch, clockhands driven by said mechanical time measuring apparatus throughthemedium of said slip clutch, electrical time measuring apparatusincluding a synchronous motor,

a source of alternating, current of regulated fife:- quency, contactscontrolled respectively by said mechanical time measuring apparatus andsaid electrical time measuring. apparatus and closed only when saidmechanical, tin e measuring apparatus and said electrical time measuringapparatus manifest the same time for initially energizing saidsynchronous motor from said source, holding contacts for maintaining ahold.- ing circuit for said motor closed until an alternating currentcessation occurs, means controlled in accordance with the difference ofthe time integration measured by said mechanical and said electricaltime measuring apparatuses for adjust ing the rate of operation of saidmechanical time measuring apparatus and acting relatively slowly seas tocause it to correctly manifest the passing of time as determined by theaverage frequency of said source applied to said synchronous motor, andmeans controlled by said electrical time measuring apparatus forperiodicallyv setting said clock hands as permitted by said slip clutch.

OSCAR H. DICKE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,328,247 Poole Jan. 13, 1920 2,185,334 Dicke Jan. 2, 19%

